Various abbreviations that appear in the specification and/or in the drawing figures are defined as follows:    3GPP third generation partnership project    UTRAN universal terrestrial radio access network    EUTRAN evolved UTRAN (LTE)    LTE long term evolution    Node B base station    eNB EUTRAN Node B (evolved Node B)    UE user equipment    EPC evolved packet core    MME mobility management entity    S-GW serving gateway    RRC radio resource control    AP access point    BS base station    CC central controller    CCCH common control channel    CSCF call state control function    EPS evolved packet system    GW gateway    HSS home subscriber server    D2D device-to-device    IP internet protocol    IMS IP multimedia subsystem    NAI network access identifier    NAS non-access stratum    PDN GW packet data network GW    SGSN serving gateway support node    RB resource block    SRB signaling radio bearer    SAE evolved system architecture    SIP session initiation protocol    TMSI temporary mobile subscriber identity    OFDMA orthogonal frequency division multiple access    CDMA code division multiple access
One specification of interest is 3GPP TS 36.300, V8.4.0 (2008-03), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (E-UTRAN); Overall description; Stage 2 (Release 8). This system may be referred to for convenience as LTE Rel-8, or simply as Rel-8. Note that this is a stage 2 specification, and may not exactly describe the system as it is currently expected to be implemented. In general, the set of specifications given generally as 3GPP TS 36.xyz (e.g., 36.311, 36.312, etc.) may be seen as describing the entire Release 8 LTE system.
Of particular interest herein are the further releases of 3GPP LTE targeted towards future IMT-A systems, referred to herein for convenience simply as LTE-Advanced (LTE-A). Reference can be made to 3GPP TR 36.913, V0.0.6 (2008-05), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for Further Advancements for E-UTRA (LTE-Advanced) (Release X).
FIG. 1A is based on FIG. 4 of 3GPP TS 36.300, and shows the overall architecture of the E-UTRAN (Rel. 8) system. The E-UTRAN system includes eNBs, providing the E-UTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UEs. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME (Mobility Management Entity), by means of an S1-MME interface, as well as to a Serving Gateway (S-GW) by means of an S1-U interface. The S1 interface supports a many-to-many relation between MMEs/Serving Gateways and eNBs.
FIG. 1B is based on FIG. 4.2.1-1 of 3GPP TS 23.401 V8.0.0 (2007-12), Technical Specification 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access (Release 8), and shows the non-roaming architecture for 3GPP accesses. In addition to the S1-MME interface shown in FIG. 1A, there is also shown an S1-U interface to a serving gateway. The serving gateway is interfaced with the MME (S11 interface), with a SGSN (S4 interface), with UTRAN (S12 interface), and with a PDN gateway (S5 interface).
IMT-A comprises radio technologies that meet the requirements currently defined by ITU for radio technologies beyond IMT-2000 (year 2010 and beyond). 3GPP is currently defining a study item to prepare LTE-Advanced that meets the IMT-Advanced requirements. Competing technologies such as WiMAX are expected to define advanced versions of current standards to be IMT-Advanced technologies. For WiMAX, standardization of IMT-Advanced technology is currently taking place in the IEEE 802.16m task group.
Aspects of IMT-A may be expected to include D2D communication to enable new types of services, as well as flexible spectrum use (FSU) to increase the spectral efficiency in a multi-operator environment.
In previous wireless communication systems (e.g., GSM, UMTS) with a circuit switched architecture it was straightforward to detect D2D traffic, as the network elements (MSC) involved in the D2D setup are a part of the cellular core network. As a result the core network could readily check if both devices were in the same cell, or in adjacent cells, to request a measurement and to setup the D2D bearer.
In addition to GSM and UMTS, D2D has also been proposed or provided in other wireless communication technologies, for example in WLAN, Hiperlan/2, and Tetra.
Various US patents and patent application Publications that generally relate in some respect to peer-to-peer and mobile-to-mobile communication include: 2006/0178148, 2006/0160544, U.S. Pat. Nos. 7,050,821, 6,904,055, 6,415,146, 6,047,178, 5,995,500 and 5,666,661.
An ability to provide D2D communication is not supported by E-UTRAN (Rel. 8).